Nanofiltration

Abstract

Nanofiltration (NF) is, formally, the pressure‐driven membrane process that fills the gap between reverse osmosis (RO) and ultrafiltration (UF). Because the name of the process was introduced and accepted rather late (in the 1980s), the process boundaries are not well defined, so that NF has features of both neighboring processes, combined with the process' own specificities. This transitional profile makes NF to an exceptionally interesting technology, particularly because it operates in the range of applications for removal of small organic solutes in the range of 200–2000 g/mol, and (partial) removal of inorganic ions, with the additional potential of separating mono‐ and multivalent ions. The combination of the dual nature of NF as a process intermediate to RO and UF and its specific challenges and opportunities are shown in this article. Membrane materials and synthesis methods are described in brief and to the extent that they differ from general methods of membrane manufacturing. Properties of membranes and membrane materials prove to be necessary for understanding the performance of filtration and separation, which will be shown through a combined approach based on experimental insights and modeling. Solvent‐resistant nanofiltration (SRNF) is described separately as one of the newly emerging membrane processes, with a very large potential for separations in the chemical, petrochemical, pharmaceutical, as well as food and related industries. The performance of SRNF will be related to physicochemical parameters, which eventually should allow prediction of the process performance. For aqueous applications, special attention is paid to membrane fouling in NF, which remains one of the main points of attention. The approach followed here is that of the resistance‐in‐series model, in which flux decline is split up into its different contributing effects, aiming at identifying and controlling the most significant contributors. It is suggested that adsorption of organic solutes and pore blocking are potentially the most important mechanisms of flux decline that are difficult to control. The most important applications of NF (in aqueous solutions) are outlined: production of drinking water (with focus on newly emerging applications such as the removal of a wide range of micropollutants), applications in wastewater treatment and water recycling, and the use of NF in fractionation processes. Finally, a brief indication is given of the challenges for NF and NF membranes that remain to be solved.

Correlation between Computed Ion Hydration Properties and Experimental Values of Sugar Transfer through Nanofiltration and Ion Exchange Membranes in Presence of Electrolyte

“…ΔEi w = EComplex − Eion − E Hyd.shell (1) Basis set superposition error (BSSE) correction [23] was applied to increase the accuracy of the calculated interaction energy [24,25].…”

“…Membrane technology is used in a number of civil and industrial applications such as the food industry, biological and chemical fields, pharmaceutical productions, water treatment, complex fluid treatment, gas separation and more [1][2][3]. Its increasing widespread use is due to its ability to meet the process intensification requirements: low energy demand, selective transport of specific compounds, potential to boost reaction processes and reduced soil consumption.…”

Ammonium Fertilizers Production from Manure: A Critical Review

“…Nanofiltration Nanofiltration membranes are characterized by a MWCO in the range of 150-300 Da, which typically displays a very high rejection (> 99%) of multivalent ions, high rejection of organic molecules larger than the MWCO (> 90%) and lower rejection of monovalent ions (48). The latter can be between 0% and 70% (48). Therefore, NF should not be efficient in the recovery of ammonia as isolated molecule or ion.…”

Nanotechnology in Wastewater Management: A New Paradigm Towards Wastewater Treatment

“…NF is one of the most significant and widely employed techniques in the field of wastewater treatment attributed to its exclusive filtration mechanism and the availability of a variety of membranes. NF is appropriate to filter out more or less all organic and inorganic contaminants, including quite a lot of harmful microbes from wastewater [114][115][116]. NF membranes are highly flexible, costeffective and easy to produce.…”